Method of producing flat printing plates



April 11, 1950 R, R, MYERS, JR 2,504,080

METHOD OF` PRODUCING FLAT PRITING PLATES Filed April 21, 194sfwn/@m2715754 Patented pr. 1.1, 195@ METHODl F PRODUCING FLAT PRINTING.PLATES Roberty R. Myers, Jr., Des Moines, Iowa, assignor to, MonorneltCompany, Incorporated, Minneapolis, Minn., a corporation of MinnesotaApplication April 21, 194:8,` Serial No. 22,374

3 Claims.

,The principalobject of my invention is to prowithoutv appreciabledistortion, thereby making for printing fidelity and accurate colorregistry in multi-color printing. A further object of this invention isto. provide aY method of making ilatv printing plates that eliminatesthe placement of the shell in a holding pan prior lto the pou-ring ofthe molten metallic backing. A stillfurther object of my invention isto4 provide a method of making flat printing plates kthat presses. themolten `backing material into the shell, thereby not only properly llingout the shell and eliminating air bubbles, but producing o, pressurecast plate.`

A still further object of my invention is to provide a method thatproducesv a at printing plate economically, quickly, and easily. Afurther object of my invention .is to eliminate any possibility of themolten backing material running under the printing shell during thebacking phase.

A still further object of this invention is to pro,- vide a method ofmaking printing plates that yeliminates much hand work, reduces the timeelement., and produces printing plates of uniform thickness. y

These and other objects will be apparent to those skilled in the art.

My invention consists in the method or process,

whereby the objects contemplated are attained as hereinafter more fullyset forth, pointed out in my claims, and illustrated in the accompanyingdrawings, in which:

. Fig. 1 is a perspective view of a printing shell with the marginaledges bent upwardly toy form compressing of the backing material ontothe plates is to take the printingV shell and place it in a pan, afterwhich the molten backingr material is poured into the pan and over theshell. Much skill and timeis necessary in this part of the operation. Itis almost impossible to pre- Vent some of the backing metal from runningbe- 2 tween the printing shell and the inside bottom of the pan. This isdue to the fact that the thin printing shells are usually warped andinasmuch as they are made of lighter material than the molten backingmaterial, they have a tendency to iloat orV rise upwardly yin the moltenmass. Skilled operators usually try to hold the shell on the bottom ofthe tray by a stick or like, but as above noted, a certain amount of thebacking plate will always rununder the shell. It is for this reason thatthe face of the printing shell before it is placed vin the pany ischalked` or otherwise coated to prevent the backing material' stickingto the face of the shell even though it does run under the same. One ofthe most time consuming phases is the pre-heating of the heavy pansbefore the introduction of the backing material. This not only takestime and heat units, but such heated pans and the backing material takea considerable time to cool, After the printing plate has been cooled itis necessary to remove it from the pan and trim it. Another disadvantageof this present method is that there `is a great waste in the backingmaterial which must be trimmed from around the edges of the shell. Also,besides trimming, any backing material on the face of the plate must beremoved and the face of the plate cleaned of chalk or like materialplaced thereon. A further disadvantage of the present method of makingplates is that the thickness of the backing material is not uniform and,of course, must be machine thinned to the proper thickness. Even,however, regardless ofthe skill and time taken, such' resultant printingplates are defective and must be re-worked to eliminate highs and lowsand other imperfections. Two reasonsl are the main causes for thesetroubles, i. e., the thin printing shell has a tendency to warp before,during, and after the heated backing material is poured onto it,and'with only the force of gravity to spread the molten backingmaterial,the backing material develops stresses and strains, internal bubbles,varying densities, and an uneven top surface. I have overcome suchproblems, as will hereinafter bey appreciated.

In Fig. l, I use the numeral Ill to designate an electroplate shell. Themethod' of obtaining such a printingv shell is'well known in the artland is not a part of this invention. Although I have particularlydesignated the numeral lll as an electroplate shell, it is obvious thatthis printing shell may be of any kind and in fact, can be an ordinarymatrix. The iirst step in my process-is to bend the marginal edgesy Ilofthe member l0 upwardly to provide a tray. If in bending the `into thetray shell.

corners, or rim edge is not of uniform height, they may be trimmed toprovide a tray as shown in Fig. 1. While it is desirable to have thecorners of the tray as tight as possible, any molten metal poured intothe tray will congeal at the corner slit or opening and seal the same.By this step in my process, I not only strengthen the shell, buteliminate the hereinbefore necessary placing of the shell in a pan priorto the application of the molten backing material. 'I'he second step inmy process is the pre-heating of the tray-shaped shell. This may beaccomplished by any suitable means such as gas or oil heat, or by anelectric heating plate I 2, as shown in Fig. 2. In this figure, I showthe tray resting on a base I3 and with the heating plate below the base.While under certain conditions, this preheating of the tray may bedispensed with, I find that by pre-heating the tray shell it will bemore receptive to the receiving of the backing material. After the shell-has been pre-heated so that the molten material will run properly intoall of the back crevices of the shell, I pour the molten backingmaterial I4 This filling of the tray shell with molten backing materialmay be considered as the third step. The fourth step consists in theagitating of the tray shell with the molten `metal therein by anysuitable means such as an air plunger agitator I5. Also, under certaincircumstances, it is possible to dispense with this fourth step in theprocess. The fifth step is the bringing of a press head IIS downwardlyon the top of the shell tray containing the molten backing material withthe press head of a dimension greater than the dimension of the tray soas to overlap and extend beyond the periphery of the tray as shown inthe drawings. This press I6 will be cold relative to the molten backingmaterial and the rst action will be for the press to chill and solidifythe upper surface of the molten material in the tray. This result willseal the upper part of the filled tray shell and as the press continuesdownwardly, the molten backing material on the top of the shell will becompressed and forced downwardly on the shell, thereby properly llingall of the crevices of the printing shell. Obviously, this pressurecasting of a printing plate will not only assure successful backing ofthe shell, but will force the shell downwardly into contact at allpoints with the flat upper surface of the base I3. This means that thebottom printing surface of the finished plate will be level at allrequired points and that highs and lows will be substantiallyeliminated. Even though the shell may be slightly warped prior to thelowering of the press, it will be definitely straightened and properlyformed in a level plane when the press is lowered onto the shell andmolten material. This substantially perfect forming of a printing plateeliminates costly and time-consuming hand labor. Another result of suchpressure casting is that the upper surface of the finished printingplate will be that of the flat press and, therefore, it will beunnecessary to reflnish the top of the backing material after it hascooled. If desired the face of the press may have corrugations II, asshown in Fig. 4, in order that the finished plate will also have topcorrugations to add to its strength. With the press in contact with thebacking material it all will quickly cool and solidify, thereby greatlyspeeding up the time of making printing plates. As soon as the backingmaterial has solidified, the press is elevated and the printing plateremoved for trimming to produce a printing plate I8, as shown in Fig. 5.I f

but only ll the vacant spaces.

the member III is a matrix, instead of a printing shell, the matrix isremoved as soon as the material I4 cools.

Brieiiy, the main phases of my process are the bending of the printingshell or like upwardly at its outer edges, the pouring of molten backingmaterial into the tray thus formed, and the application of a press tothe surface of the molten material to compress the same and solidify thesame by lowering rst its surface temperature. By regulating the distancethe press closes, all of the printing plates made thereby will be of thedesired and uniform thickness. By turning up the outer edges of theshell the present method of using a pan and the pre-heating of the sameis completely eliminated. Furthermore, there is no possibility of thebacking material running under the shell and adhering to the face of theshell. My method, therefore, eliminates the coating of the face of theshell with a chalk substance or like. Furthermore, the backing platematerial is placed in my tray shell and therefore the print'- ing shellcannot float in the backing material. By my method, the press in a fewseconds will solidify the backing plate and the present long coolingperiod is completely eliminated. Furthermore, by pressure casting theplate, as herein described, the backing material after cooled, will beof the proper density and there will be a minimum waste of the backingmaterial when the plate is trimmed at its edges. Under certaincircumstances, such as when the printing shell is exceptionally fragileand thin, it may be desirable to coat the face'of the shell with clay orlike material before it is subjected to the press. This clay or likematerial will ll the blank spaces between the reliefs of the printingshell and will prevent thereby the heavy backing material or the actionof the press from forcing these blank spaces downwardly onto the surfaceof the base of the press. Obviously, it is desirable that these blankspaces remain in elevated positions to provide the required printingsurface or characters of the plate. The clay or like should not coverthe relief indicia of the shell,

If such a substance is used on the face of the shell, it should beremoved by water or like after the plate has cooled.

Some changes may be made in my process for producing at printing plateswithout departing from the real spirit and purpose of my invention, andit is my intention to cover by my claims, any modified forms ofstructure or use of mechanical equivalents which may be reasonablyincluded within their scope.

I claim: l

1. The method of producing flat printing plates, comprising the takingof a flat bendable sheet member having relief indicia thereon and thebending of its outer marginal edges upwardly to form a tray, theplacement of the tray on a flat supporting press surface, theintroduction of a molten material into the tray with its bent edgesacting as the sole edge confining means for the molten material, thesubjection of the top of the tray and its molten contents tothe downwardpressing action of a press head of a press, with the press head surfacehaving dimensions greater than the dimensions of the tray so as tooverlap and confine the entire tray, and the removal of the press headfrom contact Awiththe .tray and material therein after the Amaterial has2. The method of producing -flat printing plates, comprising the takingof a flat bendabie sheet member having relief indicia thereon and thebending of its outer marginal edges upwardly to form a tray, theintroduction of a molten material into the tray with its bent edgesacting as the sole edge confining means for the molten material, thesubjection of the top of the tray and its molten contents to thedownward pressing action of a press head of a press, with the press headsurface having dimensions greater than the dimensions of the tray so asto overlap and conne the entire tray, and the removal of the press headfrom contact with the tray and material therein after the material hassolidified.

3. The method of producing flat printing plates, comprising the takingof a at bendable sheet member having relief indicia thereon and thebending of its outer marginal edges upwardly to form a tray, theplacement of the tray on a fiat supporting press surface, theintroduction of a solidifiable material into the tray with its bentedges acting as the sole edge confining means for the solidiablematerial, the subjection of the REFERENCES CITED The followingreferences are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 696,686 Lyons Apr. 1, 1902915,021 Dunton Mar. 9, 1909 1,009,390 Droitcour Nov. 21, 1911 1,896,690White Feb. '7, 1933 1,905,048 Norris et al Apr. 25, 1933 1,991,539Boegehold Feb. 19, 1935 2,182,114 Bungay Dec. 5, 1939 2,203,679 EdwardsJune 11, 1940

